Power clamps are known of the type in which linear actuating reciprocating movement of a fluid motor is adapted to be translated into rotary movement of a clamp arm. The clamp arm is attached to a linkage assembly or other force transmitting means which in turn is connected to the end of a piston rod of the fluid motor. In the retracted position of the fluid motor, the clamp arm is normally in a released position, that is, the clamp arm is removed from a work supporting surface. When the fluid motor is actuated, the clamp arm is pivotally moved into a clamping position to clamp the work piece to a work supporting surface and securely hold the workpiece thereto.
It is well known for such power clamps to have an open body axially aligned with and connected to the fluid motor. The open body can be mounted on a first support, wherein the body is opened at the top, bottom, and front, with a pair of opposed, spaced side plates having one end turned out and secured to the fluid motor. The open design of the body allows entry of dirt and/or other foreign matter into the interior of the body which can create problems with the internal working mechanisms of the power-operated clamp. 
Other designs have remedied this problem by providing an enclosed power-operated clamp that seals against particle intrusion and protects the internal mechanisms of the power clamp from undue wear and malfunction caused by abrasive particles and other adverse elements. Such enclosed power clamps typically use a pivoted clamp arm actuated by an internal linkage that is completely enclosed within the housing so that only a rotary shaft passing through a protective bushing extends between the enclosed linkage and an exposed exterior clamp arm.
Enclosed power clamps typically have housings fabricated from a high strength metal such as steel or steel alloys. Due to the nature of these materials, as well as the tolerances and the enclosed configurations required of an enclosed power clamp housing, enclosed power clamps are rather difficult and expensive to manufacture, especially power clamp housings. In addition, these metals tend to be relatively heavy, thereby creating extra loads on the manipulators on which the housings are attached.
Other designs have attempted to resolve the shortcomings of the enclosed power clamp by providing a housing that is fabricated from a plurality of stacked planar plates. These types of designs still have the disadvantage of having all of the planar plates fabricated from a high strength steel. In addition, such designs have the design and manufacturing concerns of having to stack and connect a plurality of planar plates to create a power clamp.
Thus, it would be desirable to provide an inexpensive and lightweight rotary clamp housing that provided the structural integrity required of a power clamp.